Maria Guadelupe Guereca Betancourt, a resident of Juarez, Mexico, lost her son Sergio, 15, when he was shot under the black bridge that spans the border from El Paso, Texas, to Juarez. Kainaz Amaria/NPR hide caption

Family members huddle at the fence to talk to loved ones living across the border. Kainaz Amaria/NPR hide caption

Parts of the fence along the U.S.-Mexico border might stop vehicles, but they don't keep out those making the journey on foot. Kainaz Amaria/NPR hide caption

Columbus, N.M., was raided by Pancho Villa in 1916 and by federal agents in 2011. Kainaz Amaria/NPR hide caption

Workers arrive at an assembly plant located along the border. Kainaz Amaria/NPR hide caption

Dob Cunningham (left) and his friend Larry Johnson look over the edge of Cunningham's 800-acre ranch in Quemado, Texas. Kainaz Amaria/NPR hide caption

The La Posada Providencia shelter in San Benito, Texas, is run by a group of nuns. While the shelter is just across the border from Mexico, the asylum seekers come from poor, troubled countries around the globe. Kainaz Amaria/NPR hide caption